Vegetative and micropropagation of leucaena
Keynote paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.
To effectively utilize sterile hybrids of leucaena, efficient protocols for vegetative propagation are needed that meet different user requirements and capabilities. We developed and compared methods for propagating several sterile hybrids of leucaena and compared them with each other and with propagation via seeds for variety K636. Methods included air-layers, rooted cuttings, grafting and tissue culture (micropropagation). All methods required 14‒20 weeks from generation of new shoots on the stock plant to production of rooted plantlets ready to outplant as compared with 6‒8 weeks for seedlings of K636. Successful rooting was highest for air-layers and rooted cuttings. Grafting had lower success owing to a higher skill requirement for the propagator. Tissue culture showed promise, but use of field-grown material was limited by microbial contamination of propagation media. Rooted cuttings are the best option presently for operational-scale propagation, but the method requires a mist system or a carefully controlled non-mist environment. If an effective method can be developed, grafting of young shoots onto a seedling rootstock is an alternative that retains the advantages of a seedling tap root and requires fewer resources than rooted cuttings or tissue culture.